This invention pertains to a novel throttle body assembly which is particularly useful in connection with an electronic fuel metering system.
The application of Kenneth A. Graham, Ser. No. 719,206 filed Aug. 30, 1976 and assigned to the same assignee as the present application, now U.S. Pat. No. 4,066,721, discloses a throttle body assembly having a novel type throttle blade. In certain respects the present invention represents an improvement upon the throttle body of that earlier application. One advantage of the present invention is that improved quality of engine operation is attained at idle and in the part throttle range encountered at light engine loads. This advantage is believed achieved with the present invention through improved mixture and atomization of fuel with the induction air. Pursuant to the present invention counter-rotatable throttle blades cooperatively define variable venturi sections which are located centrally within the induction passage and are selectively variable in effective size from idle up through the light load, part throttle range of operation. In a limited range prior to full throttle, the blades separate at the venturi sections to permit maximum air flow centrally through the throttle body between the separated blades. In achieving the improved operation with the present invention, the peripheries of the throttle blades are sealed with respect to the walls of the induction passage by improved sealing arrangements. Thus, air flow in all modes of throttle operation is confined to and selectively controlled within the central region of the induction passage. In the application of the throttle body of the present invention to an electronic fuel metering system, metered fuel jets may be poised at the central region of the induction passage directly over the venturi sections to spray fuel into the induction passage.
The foregoing features, advantages and benefits of the invention along with additional ones, will be seen in the ensuing description and claims which are to be considered in conjunction with the accompanying drawings.